Much information concerning tofu dishes are now presented, for example, in a home cooking column of Japanese papers and cook books, and tofu dishes are becoming widely popular both in homes and restaurants.
It is not so easy, however, to handle a large quantity of tofu in processing or cooking because of its fragility. For example, in the preparation of a Chinese dish, Mabo-Dofu, there are involved cutting of tofu into dice and mixing the cut pieces with condiments and thickening the seasoned soup with dogtooth violet starch. As long as tofu is handled in a small quantity and with care as in home cooking, it is not impossible to cut or mix tofu without damage or crumbling. However, tofu should suffer from crumbling to a serious extent when handled in bulk unless a specially designed apparatus is developed.
In preparing a tofu salad by mixing cut pieces of tofu and vegetables with a dressing, tofu would be similarly crumbled during mixing. In addition, the water is released from tofu when left to stand for a while to make the dressing watery and less palatable. It is therefore difficult to make large quantities of tofu salad dishes and keep them in stock.
Tofu is generally prepared through processing steps of immersion of soybeans in water, grinding to a soybean juice, heating, separation into a soymilk and an okara (residue), and coagulation of the protein by addition of a coagulant to obtain bean curd.
On the other hand, a process for easily preparing a tofu-like gel without requiring the above-described coagulation step has been proposed as described in JP-A49-7453 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), in which a tofu-like gel is obtained directly from a homogenized mixture comprising soybean protein (particularly isolated soybean protein) and water, and preferably fats and oils. The technique has undergone developments through proposals on the production of frozen tofu, dried tofu or the like foods as disclosed in JP-A-54-122755 and 58-78560. However, the tofu-like products as produced by this technique are available only in hermetically sealed packages, where the mixture of raw materials has been solidified; or the dried tofu products are utilized only as an ingredient of soups. Hence, these products are still unsatisfactory from considerations for applicability to large quantity cooking.
Although the development of freezing of tofu has succeeded in prevention of denaturation due to freezing, it has not yet achieved satisfactory restoration in original softness after thawing.
The inventors of the present invention noted that the above-described gel prepared from a homogeneous mixture of soybean protein, water, and fats and oils (hereinafter referred to as "tofu-like food"), as compared with conventional tofu, is less crumbly, and its water content is hardly released therefrom with time so that dressings or seasoned soups can be prevented from becoming watery. The inventors considered the tofu-like food promising for processing and seasoning in a large quanity because of these merits. In turn, the tofu-like food differs from conventinal tofu in mouth-feel, rather feeling like sesami tofu (a gel prepared from sesami and arrowroot starch), and is somewhat wanting in the good taste of tofu. Hence, it has been demanded to overcome such delicate differences of the tofu-like foods from tofu for particular use in tofu dishes in which tofu (or tofu-like food) plays a chief role, such as Mabo-Dofu, setting aside the case where the tofu-like food is used as an ingredient of soups.